This invention relates to the field of land graders or towed plows, of the type towed behind a tractor for active scraping, and levelling of unprepared soil or partially prepared soil, as a step in the preparation of a roadbed.
The use of powered cutters in such a device is known. For instance, U.S. Pat. No. 3,693,722 to Brown discloses a grading blade which includes parallel rotary cutters suspended transversely to a grading vehicle, such as a motor grader.
The cutters in Brown rotate around an axis transverse to the direction of travel of the grader.
U.S. Pat. No. 3,841,006 to Mironov, et al discloses a towed rotary cutting head particularly suited for terracing or cutting terraces. The cutting head is mounted forward on a heavy tractor. Again the cutting blades rotate around an axis transverse to the actual cut.
U.S. Pat. No. 4,342,162 to Spaans, et al disclose an elongate soil preparation or ground material planing device in which an elongate auger having a helical blade is used to laterally move soil.
U.S. Pat. No. 3,999,314 to Miller, et al discloses a rotating cutting tool and a method of suspending the same from an articulated prime mover.
U.S. Pat. No. 3,767,262 to Pentith discloses the use of a rotating tooth drum for removing a paved road surface.
U.S. Pat. No. 3,638,539 to Lewis discloses a road base grader utilizing in combination a helical transverse auger and a plurality of rotating scarifiers. The auger laterally displaces material loosened by the rotating scarifiers.